In conventional automatic analyzing apparatuses, an agitating method using ultrasonic waves is known as one of methods for agitating a sample, a reagent, etc. Several examples of the agitating method using ultrasonic waves are as follows. 1) A method of making cohesion of substances under agitation less likely to occur by utilizing a phenomenon that an ultrasonic wave acts upon a portion in which a difference in acoustic impedance is large, as disclosed in, e.g., JP A, 2-67963. 2) A method of vibrating a container itself and providing an agitation capability, as disclosed in, e.g., JP A, 11-230970. 3) A method of giving rise to convection due to an acoustic flow of substances themselves under agitation caused upon irradiation of an ultrasonic wave, as disclosed in, e.g., JP A, 8-146007. Those agitating methods using ultrasonic waves have advantages that since a sample, a reagent, etc. can be agitated in a contactless manner, there is no fear of contaminating other samples, reagents, etc., and that since any agitating rod is not required, the size of a reaction container can be reduced and the amounts of the sample and reagent consumed can be reduced.